Cupola furnace and process for its operation



p 2, 1958 JEAN-BAPTISTE GUILLAMON 2,850,374

CUPOLA FURNACE. AND PROCESS FOR ITS OPERATION 2 Sheets-Sheet 1 II/VVENTOR JEAN BAPTIST/f GUILMMUIY Filed Ha P 2, 1958 JEAN-'BAPTISTE GUILLAMON 2,850,374

CUPOLA FURNACE, AND PROCESS FOR ITS OPERATION A Filed May a1, 1956 2 Sheets-Sheet 2 IN vE/v TOR IBM/BAP 7/5715 GZl/L 1/4/1400 5 QWM ATTORNEYS United States Patent CUPDLA FURNACE AND PROCESS FOR ITS. OPERATION It has already been proposed to operate cupola furnaces having a fore-hearth or of the continuous casting type by providing in the bottom of the cupola furnace a heating hearth with a maximum temperature area in register with said hearth as obtained through a suitable adjustment of the amount of air blown into the lower section of the cupola takinginto account the distance between the air-blowing twyers and the hearth.

This leads to the obtainment of cast iron at a very high temperature which may be modified at will through special structural features of the cupola.

It is possible to adjust the flow of the combustion gases and their temperature with a view to defining the chemical composition of the gases which allows ascertaining the output of air blown at room temperature.

Now, it has been found that the combustion gases were subjected under the action of a same disturbance to modifications which are all the more important when their temperature is higher, which makes the adjustment of their flow very diificult, if not impossible.

Furthermore, the removal of the burnt gases at very high temperatures requires pipes of refractory material which are very expensive and this leads to problems of safety, working conditions and sanitation, the satisfactory solution of which requires a large expenditure of money.

In order to cut out these drawbacks and to allow uniformizing the throughput of combustion gases, I have conceived, in accordance with my invention, of the cooling of said gases through a circulation and/or spraying of Water.

The temperature of the gases is thus reduced down to avalue for which the amplitude of modification is sufficiently small for it to be possible to resort to automatic flow adjusting apparatus of a conventional type, with which may be incorporated any known thermometric or thermoelectric arrangement for the automatic correction of the flow as a function of temperature while taking as a reference the flow at 0 C. under an atmospheric pressure of 769 mm. of mercury.

The composition of the combustion gases is speedily stabilized as soon as the permanent conditions of operation of the cupola furnace are reached and consequently, assuming Q designates the constant flow from the blower feeding the air-blowing twyers, q designates the flow of the combustion gases corresponding to a volume q blown towards the lower part of the cupola furnace, the volume of air blown into the upper part of the furnace is This double adjustment allows retaining substantial uniformity in composition for the case iron and the modifications of q alone allow modifying it as desired. The temperature is much less subjected to the action of this modification in the flow of the combustion gases and consequently my improved method allows modifying the composition of the cast iron while retaining a high temperature of casting.

My invention has also for its object various improved structural modifications brought to cupola furnaces provided with a fore-hearth with a view to improvingv the execution of the method.

Among these modifications, I should mention more particularly:

The arrangement of a baffle plate at the upper end of the syphon servingfor the exhaust of the combustion gases with a view to stopping the steam formed by the dropping of the dross into the water of the vat, serving for the granulation of the slag.

The cooling of the wall of the syphon through circulation and/ or spraying of water,

The adjustment of the level of water inside the slaggranulating or dross-containing vat together with the keeping of the slideways of the dampers associated with the latter in a constant state of cleanliness through the operation of a set of sliding dampers provided preferably on a same slopingwall of the vat.

I have illustrated in the accompanyingdrawings by way' of example and by no means in a limiting'sense various embodiments of my improved arrangements incorporated with cupola furnaces of the fore-hearth type for the execution of my method. In said drawings:

Fig. l is a diagrammatic elevational view of ,a cupola furnace provided with its fore-hearth.

Fig. 2 is. a vertical sectional view of the lower part of the cupola furnace and'ofits fore-hearth.

Fig. 3 is a. partial sectional view through line II IIII of Fig. 4 of the vat containing the dross and serving forv the granulation of the slag and the exhaust of the gases, the syphon being assumed to be removed.

Fig. 4 is a sectional view through line IV-IV' of Fig.3.

In Fig. 1, 1 designates the cupola furnace, 2 its forehearth, 3 the syphon for the vat 4 containingthe dross. and in which the slag is granulated, 5 the exhaust pipe for the combustion gases together with its jacket 6 forming the water circuit, 7 the fan or blower for blowing air into the furnace, 8 a gate for adjusting the fiow of air blown into the furnace, which gate is controlledby the motor 9 and is inserted inthe air feeding pipe10 lead: ing to the blast box. The exhaustpipe 5 includes ex: tension 11 of a reduced height assembled through flanges 12 providing for a sealing of the stream of gases. An expansion compensating packing may be provided at 13 for absorbing the modifications in length ofthe pipe e1e ments under the action of temperature, 14 designates an adjusting throttle valve inserted in the gas exhaust ,pipe

and controlled by an auxiliary motor 15.

Fig. 2 also shows the cupola furnace 1 with its forehearth 2 provided with a cap 16 while 17 designates the air-blowing twyers. The air is directedpartly towards the upper part of the cupola furnace and partly towards the hearth 18. For a predetermined distance between said hearth and the twyers 17, the cross-section of the channel 19 connecting the cupola furnace with the forehearth should be such that, taking into account the re-v sistance formed in the upward direction by the stack of alternating coke and metal layers, the amount of air admitted into the fore-hearth 2 may be exactly that required for the formation of a maximum temperature area at the distance considered from the twyers i. e. on the hearth 18. 21 designates the opening for the removal of the dross from the fore-hearth.

Each time the dross is to be removed, the dropping of the slag into the water of the granulating vat leads to the production of an amount of steam which varies with the mass and temperature of the slag. In order to prevent said steam from disturbing the adjustment performed through admixture with the combustion gases, a baflie plate 27 (Fig. 3) prevents said steam from entering the uppersection of the syphon 3 while simultaneously the walls of the syphon are cooled through water running and/or spraying over them so as to make the steam evolved condense on said walls. The combustion gases are thus simultaneously cooled. To allow the expansion under the action of heat to be performed freely, the syphon 3 is secured to the ferrule 23 of the fore-hearth independently of the slag-granulating vat 4 into which it'dips.

The syphon '3 is provided at its front end with an inspection gate 28 secured to the actual body of the syphon with the interposition of a fluidtight packing. An inspection hole adapted to operate in two directions allows checking the flow of the slag and acting if required inside the syphon.

One of the walls 30 of the dross-containing and slaggranulating vat 4 has a sloping shape as shown in Fig. 4 so as to aid in the extraction of the granulated slag. This extraction may be performed mechanically through a chain of scrapers or of buckets.

The level of the water inside the vat varies with the adjustment and consequently, with a view to cutting out any loss of gases which might, in addition to a disturbance in the operation of the furnace, lead'to a. poisoning of the attendants, it is necessary to suitably adjust this level since if the lowering of the level due to the pressure of the gases inside the syphon 3 is small and if, at the same time, the adjusted level is too high, the slag is cooled too near the passage 19 so that it becomes solid and prevents the removal of the dross.

In order to allow a speedy adjustment of said level, the vat 4 is provided with a damper 31 sliding between two slideways with the level N of the water inside the vat being defined by the upper edge of the damper 31.

To keep the slideways in a state of constant cleanliness, an opening 32is formed at the lower end of the slideways so as to establish a permanent circulation of water which carries along with it the foreign particles which might foul the .slideway. The water entering the vat at 33 collects in a chamber 34 engaging the bottom wall of the vat on the outside thereof and the lower opening of which allows the overflow water to be exhausted into a drain.

In the lower part of the sloping wall 30 is provided another damper 35 which may be controlled from a point above the vat andwhich provides for speedily emptying said vat 4.

What I claim is:

1. In a cupola furnace the combination of a fore-hearth, a dross-containing and slag-granulating vat, a syphon connecting the fore-hearth with the vat, a channel for the exhausting of the combustion gases connected with said syphon and a cooling water-jacket surrounding said channel.

2. In a cupola furnace the combination of a forehearth, a dross-containing and slag-granulating vat, a

syphon connecting the fore-hearth with the vat, a bafile plate at the upper end of the syphon adapted to prevent the steam passing out of the vat from mixing with the combustion gases, a channel for the exhausting of the combustion gases connected with said syphon and a cooling water-jacket surrounding said channel.

3. In a cupola furnace, the combination of a forehearth, a dross-containing and slag-granulating vat, a syphon connecting the fore-hearth with the vat, means for cooling the walls of the syphon, a baffle plate at the upper'end of the syphon adapted to prevent the steam passing out of the vat from mixing with the combustion gases, a channel for the exhausting of the combustion gases connected with said syphon and a cooling waterjacket surrounding said channel.

4. In a cupola furnace, the combination of a forehearth, a dross-containing and slag-granulatingvat, a set of parallel slideways along one wall of the vat, at least one damper slidingly carried'between said slideways and the operation ofwhich provides adjustment of the level of water in the vat by defining an overfiow'level for the water, a syphon connecting the fore-hearth with the vat, a channel for the exhausting of the combustion gases con nected with said syphon and a cooling water-jacket surrounding said channel.

I 5. In a cupola furnace, the combination of atomhearth, a dross-containing and slag-granulating vat, a set of parallel slideways along one wall of the vat, at least one damper slidingly carried between said slideways and the operation of which provides adjustment of the level of Water in the vat by defining an overflow level for the water, an exhaust opening being provided in register with the lower ends of the slideways for the removal of foul ing material, a syphon connecting the fore-hearth with v the vat, a channel for the exhausting of the combustion gases connected with said syphon and a cooling water jacket surrounding said channel.

'6. In a cupola furnace, the combination'of a fore-1 hearth, a dross-containing and sla'g-granulating vat, a set of parallel slideways along one wall of the vat, at least one damper slidingly carried between said slideways and the operation of which provides adjustmentof the level of water in the vat by defining an overflow level for the water, an exhaust opening being provided in register with the lower 'endsof the slideways for the removal offouling material, a syphon connecting the fore-hearth with the vat, meansfor cooling the walls of the syphon, a baifie plate at the upper. end of the syphon adapted to prevent the steam passing out of the vat from mixingwith the combustion gases, a channel for the exhausting of the combustion gases connected with said syphon and a cooling water-jacket surrounding said channel.

7. Process of producing cast-iron of a desired composi tion in a cupola furnace having a fore-hearth consisting in creating an area of heat at a very high temperature in the bottom of said cupola, introducing air into said area, passing a portion of the gas of combustion and air mixture from said area into said fore-hearth maintaining the casting of the molten iron in said fore-hearthat a high temperature, regulating the flow of said gas and air mixture through said fore-hearth for obtaining insaid fore-hearth a casting of a composition as desired while maintaining said casting at a very high temperature and cooling the gas leaving said fore-hearth.

References Cited in the file of this patent 1 UNITED STATES PATENTS 

7. PROCESS OF PRODUCING CAST-IRON OF A DESIRED COMPOSITION IN A CUPOLA FURNACE HAVING A FORE-HEARTH CONSISTING IN CREATING AN AREA OF HEAT AT A VERY HIGH TEMPERATURE IN THE BOTTOM OF SAID CUPOLA, INTRODUCING AIR INTO SAID AREA, PASSING A PORTION OF THE GAS OF COMBUSTION AND AIR MIXTURE FROM SAID AREA INTO SAID FORE-HEARTH MAINTAINING THE CASTING OF THE MOLTEN IRON IN SAIF FORE-HEARTH AT A HIGH TEMPERATURE, REGULATING THE FLOW OF SAID GAS AND AIR MIXTURE THROUGH SAID FORE-HEARTH FOR OBTAINING IN SAID FORE-HEARTH A CASTING OF A COMPOSITION AS DESIRED WHILE MAINTAINING SAID CASTING AT A VERY HIGH TEMPERATURE AND COOLING THE GAS LEAVING SAID FORE-HEARTH. 